problem with PHP_SELF

Hi All I would like to submit a form to call itself, and according to some references I could use the $PHP_SELF variable in action attribute of the form element in a HTML document But it is not working for me, please help. I have this line of code <form action="<?php echo $PHP_SELF; ?>" method="POST" > in the html source page, I get <form action="" method="POST"> Can anyone advice what did I missed here? Would this have anything to do with php or/and apache configuration? Thanks /dl